Small kidney of unknown cause (N27) ICD-10-CM
The N27 code range covers small kidney of unknown cause with 4 ICD-10-CM diagnosis codes. 3 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Includes
This note appears immediately under a three character code title to further define, or give examples of, the content of the category.
- oligonephronia
Codes in the N27 Range 4 codes · 3 billable
About the N27 Code Range
ICD-10 code N27 covers conditions where a kidney is unusually small without a known cause, including cases affecting one kidney (unilateral), both kidneys (bilateral), or when the side is unspecified. These codes help specify the diagnosis for medical records and treatment planning.
This section includes N27.0 for a small kidney on one side (sometimes called small left kidney or small right kidney), and N27.1 for small kidneys on both sides, also known as bilateral small kidney. If the documentation doesn’t specify which kidney is affected, N27.9 applies, encompassing terms like "contracted kidney" or "irregularly contracted kidney." Using the correct code ensures clarity when coding for "small kidney," "small left kidney," or "small right kidney" conditions of unknown origin. Medical coders looking for the ICD-10 code for small kidney will find this block is dedicated to identifying those unusual kidney size findings without a clear cause, allowing precise classification in clinical and billing contexts.
Questions About This Page
How many billable codes are in the N27 range?
Of the 4 codes in this range, 3 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the N27 range classify?
The range classifies small kidney of unknown cause. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
